MOSCOW (AP) — The Russian parliament's lower house has endorsed the country's annexation of Crimea.

The Kremlin-controlled State Duma voted Thursday to allow Crimea to join Russia following a quick discussion in which members assailed the Ukrainian authorities.

The merger needs to be rubber-stamped by the upper house and signed by Russian President Vladimir Putin, formalities expected to be completed by the end of the week.

The endorsement follows Crimea's referendum last weekend where there was overwhelming support for breaking off from Ukraine and joining Russia.

The vote, held just two weeks after the Black Sea peninsula was overtaken by Russian forces, has been rejected as unlawful by Ukraine and Western powers. The United States and the European Union have responded by slapping some limited sanctions on Russia.

A pro-Russia self-defense force member holds a gun during the seizure of the Ukrainian corvette Khmelnitsky in Sevastopol, Crimea. Pro-Russia militants boarded and seized two Ukrainian warships, the Khmelnitsky and the Lutsk.
Andrew Lubimov, AP

Russian forces arrest Ukrainian army officers during an operation on March 18 in Simferopol. Russian President Vladimir Putin has signed a treaty claiming the Black Sea region of Crimea as Russian territory.
Alisa Borovikova, AFP/Getty Images

A man holds an old Soviet Russia flag outside the parliament building on March 17 in Simferopol, Crimea, Ukraine. In a controversial vote, Crimeans have decided to leave the Ukraine and join Russia.
Hannibal Hanschke, epa

A Ukrainian boy, wearing a military uniform for children and a toy gun, looks on while attending a rally for peace, organized in reaction to the Crimean referendum, at Independence Square in Kiev, Ukraine.
Robert Chement, epa

A Ukrainian member of the Maidan self-defense force sits on his motorcycle helmet while speaking on his cellphone during a rally for peace organized in reaction to the Crimean referendum, at Independence Square in Kiev.
Robert Chement, epa

A demonstrator holds a placard reading "World - your support is our lives" during a protest against Russia's intervention in Ukraine and the referendum in Crimea in front of the Russian embassy in Vilnius.
Petras Malukas, AFP/Getty Images